Text/imessage issues!

I just got my new Samsung Galaxy s4 and I previously had an iPhone and used iMessage for texting with 90% of my family and friends. Now that I have switched everyone is still sending me imessages and I'm not getting them at all. They tell me that on their end there is no option to send me a regular text...? I have turned off imessage on my old iphone and my ipad hoping that it would force these messages to come through as regular texts to my new phone but they are still not coming through at all. Has anyone else made the switch from iPhone to Android and had this issue? How can I resolve? TIA!